A nonrandomized trial of vitamin D supplementation for Barrett's esophagus. oleh Linda C Cummings, Prashanthi N Thota, Joseph E Willis, Yanwen Chen, Gregory S Cooper, Nancy Furey, Beth Bednarchik, Bronia M Alashkar, John Dumot, Ashley L Faulx, Stephen P Fink, Adam M Kresak, Basel Abusneineh, Jill Barnholtz-Sloan, Patrick Leahy, Martina L Veigl, Amitabh Chak, Sanford D Markowitz